Determining the position and role of MafB and Krox20 in the cardiac neural crest cell gene regulatory program

 描述(申请人提供)：心脏神经脊是一组独特的细胞，它们在胚胎中经历广泛的迁移，有助于心脏发育的许多方面，包括室间隔的形成，心脏流出道的分割，以及心脏瓣膜的发育。心脏神经脊的缺陷是许多在活产中发现的先天性心脏缺陷的根源，这些问题通常 需要手术修复。尽管这在人类发育中具有明显的重要性，但我们对心脏神经脊生物学的理解仍然不完整。在这里，我们建议确定两个转录因子，MafB和Krox20，在心脏神经脊的发育中的作用。有趣的是，这两个因子在迁移的心脏神经脊中表达，而在其他迁移的神经脊种群中不表达，这表明它们在心脏神经脊的发育中发挥着特定的作用。作为转录因子，MafB和Krox20可以调节额外基因的表达，从而对心脏神经脊细胞的行为产生广泛的影响。通过消除鸡心脏神经脊中的MafB和Krox20功能，我们将识别任何由此产生的缺陷。我们假设MafB或Krox20的缺失将导致与许多先天性心脏缺陷非常相似的心脏缺陷，从而证明这些基因产物对正常心脏神经脊发育的重要性。为了实现这些目标，我们不仅将通过基于候选和系统水平的实验来研究心脏形态，而且还将研究心脏神经脊细胞所走的迁移路径，以及靶下游基因的表达。我们还将确定MafB和Krox20表达的重要转录输入。在这些实验之后，我们将组装一个基因调控网络模型，该模型描述了心脏神经脊MafB和Krox20上下游的基因表达级联，并提供了必要的框架来确定是什么使心脏神经脊有别于其他神经脊线。这一知识将为未来的研究提供信息，在这些研究中，其他神经脊细胞将被重新编程，以补偿心脏神经脊的丢失，从而挽救与心脏神经脊相关的先天性心脏缺陷。

 DESCRIPTION (provided by applicant): The cardiac neural crest is a unique population of cells that undergo extensive migration through the embryo and contribute to many aspects of cardiac development, including the formation of the interventricular septum, the partitioning of the cardiac outflow tract, and the development of the heart valves. Defects in cardiac neural crest are at the root of many congenital heart defects found in live births, and these issues often require surgical repair. Despite this clear importance in human development, our understanding of cardiac neural crest biology remains incomplete. Here we propose to determine the role of two transcription factors, MafB and Krox20, in the development of the cardiac neural crest. Interestingly, these two factors are expressed in the migrating cardiac neural crest, and not in other migrating neural crest populations, suggesting that they play specific roles in cardiac neural crest development. As transcription factors, MafB and Krox20 function to regulate expression of additional genes, and thereby they can have broad impacts on the behavior of the cardiac neural crest cells. By eliminating MafB and Krox20 function in the chick cardiac neural crest we will identify any resulting defects. We hypothesize that loss of MafB or Krox20 will result in cardiac defects that closely resemble many congenital heart defects, and thereby demonstrate the importance of these gene products for normal cardiac neural crest development. To achieve these goals, we will examine not only cardiac morphology, but also the migratory path taken by the cardiac neural crest cells, as well as the expression of target downstream genes through candidate-based and systems-level experiments. We will also identify important transcriptional inputs into MafB and Krox20 expression. Following these experiments, we will assemble a gene regulatory network model that describes the cascade of gene expression upstream and downstream of MafB and Krox20 in the cardiac neural crest, and provides the necessary framework to determine what makes the cardiac neural crest unique from other neural crest linages. This knowledge will inform future studies in which other neural crest cells will be "reprogrammed" to compensate for loss of cardiac neural crest, and thereby rescue cardiac neural crest-related congenital heart defects.